Summary

During larval development, Drosophila imaginal discs increase in size about 1000-fold and cells are instructed to acquire distinct fates as a function of their position. The secreted signaling molecules Wingless and Decapentaplegic have been implicated as sources of positional information that globally control growth and patterning. Evidence has also been presented that local cell interactions play an important role in controlling cell proliferation in imaginal discs. As a first step to understanding how patterning cues influence growth we investigated the effects of blocking cell division at different times and in spatially controlled manner by inactivation of the mitotic kinase Cdc2 in developing imaginal discs. We find that cell growth continues after inactivation of Cdc2, with little effect on overall patterning. The mechanisms that regulate size of the disc therefore do not function by regulating cell division, but appear to act primarily by regulating size in terms of physical distance or tissue volume.

Huntington's disease results in selective neurodegeneration in the forebrain and eventually death; there is currently no cure or therapy to slow its onset. Now, Ali Brivanlou and colleagues describe how isogenic stem cell lines with HTT repeat expansions give insights into the disease's cellular aetiology.

The resources pages of the Node and the BSDB have been combined and refurbished, with the new page designed to provide a range of useful links, including information on advocacy and outreach, new teaching resources for schools and databases for a wide range of species.